Before I set up my tent, I drew a half circle before the hollow

Before I set up my tent, I drew a half circle before the hollow place, which took in about ten yards in its semi-diameter from the rock, and twenty yards in its diameter, from its beginning and ending.
In this half circle I pitch two rows of strong stakes, driving them into the ground till they stood very firm like piles, the biggest end being out of the ground about five foot and half, and sharpened on the top. The two rows did not stand above six inches from one another.

Question:

A. Identify the author and the title of the novel from which the quoted part is taken.
B. Who is the narrator?
C. Why did the narrator set up a tent?
【正确答案】：A.Daniel Defoe Robinson Crusoe.
B. Robinson Crusoe.
C. When the narrator went to sea, gets shipwrecked and marooned on an island, he had to live in the tent.